ALL FIT: Episode 3 TRAINING PRINCIPLES Slim explains the need for an organized approach to fitness. At Slim's Gym, Slim and Slenda explain the importance of fitness Guidelines (F.I.T.).... more &raquo Slim and Slenda explain to the All fit Team and viewers that frequency, intensity, and time are the three important Training Principles. Slenda demonstrates a beginning work-out, a strength and endurance exercise, and a cool-down exercise. After Slim reviews the fitness Guidelines, he goes to the Body Lab where he explains the three principles of exercise: overload, progression, and specificity. Slim names the longest muscle in the body, the sartorius.&laquo less